1. The Field of the Invention
The present invention relates to improved dental compositions and methods for treating teeth surfaces. More particularly, the present invention is directed to high viscosity dental compositions, such as tooth bleaching compositions, having significantly improved effectiveness and sustained release activity. The dental compositions may advantageously be used in combination with a dental tray having reservoirs for holding the dental composition located adjacent the teeth surfaces to be treated.
2. The Prior Art
Virtually all people desire white or whiter teeth. To achieve this goal, people either have veneers placed over their teeth or have their teeth chemically bleached. In the past, patients who desired to have their teeth bleached had to submit to conventional in-office bleaching techniques. This usually involved carefully placing a hydrogen peroxide solution (typically 30% H.sub.2 O.sub.2) on the teeth, protecting the sensitive soft tissues with a ligated rubber dam, and applying heat to the solution. Such treatments typically last 30 minutes to 1 hour with from 4 to 10 appointments being necessary for a significant change. Only the labial surface of the 6-8 front teeth is treated.
Since its introduction in early 1989, there has been a growing interest among the dental profession in home-use tooth bleaching products and methods. A current representative technique includes: (1) making an alginate impression of the patient's teeth; (2) making a stone cast of the impression; (3) vacuum forming a tray from the cast, usually from thin (0.020-0.030 inch) hard transparent material; (4) instructing the patient to (a) place 2-3 drops of a bleaching solution into each area of each tooth to be bleached, (b) place the tray in the mouth, (3) expectorate any excess bleaching solution, (4) change the bleaching solution every 1 to 2.5 hours, and (5) remove the tray during meals. A few recommend wearing the tray during the night.
The most commonly used dental bleaching agent is 10% carbamide peroxide (CO(NH.sub.2).sub.2 H.sub.2 O.sub.2), also called urea hydrogen peroxide, hydrogen peroxide carbamide, and perhydrol-urea. Carbamide peroxide has been recommended and prescribed by dental clinicians since the 1960's as an oral antiseptic. Tooth bleaching was a side effect of extended usage. Over the counter ("OTC") compositions of 10% carbamide peroxide are available as "Gly-Oxide" by Marion Laboratories and "Proxigel" by Reed and Carnrick.
Positive results using the foregoing technique have been reported. The effectiveness depends upon such factors as type and intensity of stain, bleaching agent contact time on teeth, and amount of available active ingredient in the bleaching agent. Because the time commitment for the actual bleaching process takes place outside the dental office, the cost for the procedure is substantially less than conventional in-office bleaching techniques. Moreover, patient discomfort associated with home-use tooth bleaching techniques both during and after treatment is reportedly less than that associated with conventional in-office bleaching.
Notwithstanding the foregoing advantages, there remain some important disadvantages to home-use bleaching products and techniques. One important disadvantage is that either the bleaching agent must be frequently replaced during the day or the treatment extend for several weeks or months. Clinical test results indicate that saliva dilution and swallowing of the bleaching agent caused the volume of agent in the tray to diminish rapidly over time, thereby decreasing the amount of active ingredient available for tooth bleaching. Test results show that after one hour, less than one-half the original volume of bleaching agent was present. Thus, existing bleaching agents should be replenished about every hour in order to be effective.
Since current home-use bleaching agents must be frequently replenished, the user necessarily ingests large volumes of the bleaching agent. In many cases, ingestion of the bleaching agent causes sore throats. Some researchers have even suggested that long term repeated ingestion of large quantities of carbamide peroxide may be carcinogenic. Therefore, patient ingestion of dental bleaching compositions should be minimized.
Many patient's daytime schedules do not permit them to constantly replenish the bleaching agent. In addition, even the suggestion of periodically replenishing the bleaching agent during the night would not be favorably received by most patient's. Because of the inconvenience of constantly replacing the dental agent, patient compliance is difficult to maintain, and since patient compliance determines the ultimate success of the treatment, the need to constantly replace the dental bleaching agent is a major inconvenience which limits the success of the treatment.
Another disadvantage with current home-use bleaching compositions and techniques is that it often takes weeks to see an observable result. Although some have reported lightening of teeth in shorter periods of time, in most cases the home-use bleaching treatment lasts from 4 to 6 weeks. Under such circumstances, patients often lose their enthusiasm for the procedure and often stop complying with the treatment regimen.
From the foregoing, it will be appreciated that what is needed in the art are improved compositions and methods for treating tooth surfaces which facilitate patient compliance, so that the ultimate purpose of the treatment is realized.
Additionally, it would be a significant advancement in the art to provide sustained release dental compositions for treating tooth surfaces which do not need to be continuously replaced so that patient compliance is enhanced.
It would be another significant advancement in the art to provide dental compositions for treating tooth surfaces which provide a more constant level of dental agent in contact with the teeth surfaces rather than periodic high and low levels of the dental agent in contact with the patient's teeth.
It would be an additional advancement in the art to provide dental compositions and methods for bleaching a patient's teeth which provide noticeable lightening in a matter of days rather than weeks.
Such dental compositions and methods for treating tooth surfaces are disclosed and claimed herein.